1. Field of the Invention
The invention relates in general to a reversing sensor without a control box, and more particularly a master-slave type of sensor architecture to form a reversing sensor for a vehicle, wherein a master-sensor not only can take charge of detecting an obstacle but also can coordinate an operation timing for each slave-sensor and collect a detection result of the slave sensors.
2. Description of the Related Art
Among quickly developing technology, reversing sensors for automobiles are becoming widely used to assist drivers in backing up a vehicle safely. The sensitivity of a reversing sensor is directly related to a configuration setting and the number of sensors used.
With reference to FIG. 4, a conventional reversing sensor having multiple sensors includes a control box 80 connected to multiple ultrasonic sensors 81˜84. Each of the multiple ultrasonic sensors 81˜84 is connected to the control box 80 via a cable. The control box 80 coordinates the sensors to detect an obstacle.
Moreover, the connection cable between the ultrasonic sensors 81˜84 and the control box 80 includes at least a power signal line and a two-way data transmission line. Thereby each of the ultrasonic sensors 81˜84 has to be connected with the control box 80 via a 4-pin cable. When using the aforesaid connection method, the control box 80 is installed inside a vehicle and the ultrasonic sensors 81˜84 are installed on a rear bumper. Under such conditions, a cable length between the control box 80 and the ultrasonic sensors 81˜84 usually cannot be shorter than 2.5 meters. Therefore line material cost is rather high and also the long data line is likely to be affected by interference.
On the other hand, there is also a problem when testing parts of a vehicle and assembling the vehicle. Since the ultrasonic sensors 81˜84 are installed on the rear bumper whereas the control box 80 is installed inside the vehicle, the function of the reversing sensor cannot be tested before the rear bumper is attached to the vehicle. Hence it is rather inconvenient for installation and testing operations, so as to reduce production efficiency.